Aegisub/src/audio_renderer_spectrum.cpp

// Copyright (c) 2005-2006, Rodrigo Braz Monteiro
// Copyright (c) 2006-2010, Niels Martin Hansen
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are met:
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//     this list of conditions and the following disclaimer.
//   * Redistributions in binary form must reproduce the above copyright notice,
//     this list of conditions and the following disclaimer in the documentation
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// Aegisub Project http://www.aegisub.org/

/// @file audio_renderer_spectrum.cpp
/// @brief Caching frequency-power spectrum renderer for audio display
/// @ingroup audio_ui

#include "audio_renderer_spectrum.h"

#include "audio_colorscheme.h"
#ifndef WITH_FFTW3
#include "fft.h"
#endif

#include <libaegisub/audio/provider.h>
#include <libaegisub/make_unique.h>

#include <algorithm>

#include <wx/image.h>
#include <wx/dcmemory.h>

/// Allocates blocks of derived data for the audio spectrum
struct AudioSpectrumCacheBlockFactory {
	typedef std::unique_ptr<float, std::default_delete<float[]>> BlockType;

	/// Pointer back to the owning spectrum renderer
	AudioSpectrumRenderer *spectrum;

	/// @brief Allocate and fill a data block
	/// @param i Index of the block to produce data for
	/// @return Newly allocated and filled block
	///
	/// The filling is delegated to the spectrum renderer
	BlockType ProduceBlock(size_t i)
	{
		auto res = new float[((size_t)1)<<spectrum->derivation_size];
		spectrum->FillBlock(i, res);
		return BlockType(res);
	}

	/// @brief Calculate the in-memory size of a spec
	/// @return The size in bytes of a spectrum cache block
	size_t GetBlockSize() const
	{
		return sizeof(float) << spectrum->derivation_size;
	}
};

/// @brief Cache for audio spectrum frequency-power data
class AudioSpectrumCache
: public DataBlockCache<float, 10, AudioSpectrumCacheBlockFactory> {
public:
	AudioSpectrumCache(size_t block_count, AudioSpectrumRenderer *renderer)
	: DataBlockCache(block_count, AudioSpectrumCacheBlockFactory{renderer})
	{
	}
};

AudioSpectrumRenderer::AudioSpectrumRenderer(std::string const& color_scheme_name)
{
	colors.reserve(AudioStyle_MAX);
	for (int i = 0; i < AudioStyle_MAX; ++i)
		colors.emplace_back(12, color_scheme_name, i);
}

AudioSpectrumRenderer::~AudioSpectrumRenderer()
{
	// This sequence will clean up
	provider = nullptr;
	RecreateCache();
}

void AudioSpectrumRenderer::RecreateCache()
{
#ifdef WITH_FFTW3
	if (dft_plan)
	{
		fftw_destroy_plan(dft_plan);
		fftw_free(dft_input);
		fftw_free(dft_output);
		dft_plan = nullptr;
		dft_input = nullptr;
		dft_output = nullptr;
	}
#endif

	if (provider)
	{
		size_t block_count = (size_t)((provider->GetNumSamples() + ((size_t)1<<derivation_dist) - 1) >> derivation_dist);
		cache = agi::make_unique<AudioSpectrumCache>(block_count, this);

#ifdef WITH_FFTW3
		dft_input = fftw_alloc_real(2<<derivation_size);
		dft_output = fftw_alloc_complex(2<<derivation_size);
		dft_plan = fftw_plan_dft_r2c_1d(
			2<<derivation_size,
			dft_input,
			dft_output,
			FFTW_MEASURE);
#else
		// Allocate scratch for 6x the derivation size:
		// 2x for the input sample data
		// 2x for the real part of the output
		// 2x for the imaginary part of the output
		fft_scratch.resize(6 << derivation_size);
#endif
		audio_scratch.resize(2 << derivation_size);
	}
}

void AudioSpectrumRenderer::OnSetProvider()
{
	RecreateCache();
}

void AudioSpectrumRenderer::SetResolution(size_t _derivation_size, size_t _derivation_dist)
{
	if (derivation_dist != _derivation_dist)
	{
		derivation_dist = _derivation_dist;
		if (cache)
			cache->Age(0);
	}

	if (derivation_size != _derivation_size)
	{
		derivation_size = _derivation_size;
		RecreateCache();
	}
}

template<class T>
void AudioSpectrumRenderer::ConvertToFloat(size_t count, T *dest) {
	for (size_t si = 0; si < count; ++si)
	{
		dest[si] = (T)(audio_scratch[si]) / 32768.0;
	}
}

void AudioSpectrumRenderer::FillBlock(size_t block_index, float *block)
{
	assert(cache);
	assert(block);

	int64_t first_sample = (((int64_t)block_index) << derivation_dist) - ((int64_t)1 << derivation_size);
	provider->GetInt16MonoAudio(audio_scratch.data(), first_sample, 2 << derivation_size);

#ifdef WITH_FFTW3
	ConvertToFloat(2 << derivation_size, dft_input);

	fftw_execute(dft_plan);

	double scale_factor = 9 / sqrt(2 << (derivation_size + 1));

	fftw_complex *o = dft_output;
	for (size_t si = (size_t)1<<derivation_size; si > 0; --si)
	{
		*block++ = log10( sqrt(o[0][0] * o[0][0] + o[0][1] * o[0][1]) * scale_factor + 1 );
		o++;
	}
#else
	ConvertToFloat(2 << derivation_size, &fft_scratch[0]);

	float *fft_input = &fft_scratch[0];
	float *fft_real = &fft_scratch[0] + (2 << derivation_size);
	float *fft_imag = &fft_scratch[0] + (4 << derivation_size);

	FFT fft;
	fft.Transform(2<<derivation_size, fft_input, fft_real, fft_imag);

	float scale_factor = 9 / sqrt(2 * (float)(2<<derivation_size));

	for (size_t si = 1<<derivation_size; si > 0; --si)
	{
		// With x in range [0;1], log10(x*9+1) will also be in range [0;1],
		// although the FFT output can apparently get greater magnitudes than 1
		// despite the input being limited to [-1;+1).
		*block++ = log10( sqrt(*fft_real * *fft_real + *fft_imag * *fft_imag) * scale_factor + 1 );
		fft_real++; fft_imag++;
	}
#endif
}

void AudioSpectrumRenderer::Render(wxBitmap &bmp, int start, AudioRenderingStyle style)
{
	if (!cache)
		return;

	assert(bmp.IsOk());

	int end = start + bmp.GetWidth();

	assert(start >= 0);
	assert(end >= start);

	// Prepare an image buffer to write
	wxImage img(bmp.GetSize());
	unsigned char *imgdata = img.GetData();
	ptrdiff_t stride = img.GetWidth()*3;
	int imgheight = img.GetHeight();

	const AudioColorScheme *pal = &colors[style];

	/// @todo Make minband and maxband configurable
	int minband = 0;
	int maxband = 1 << derivation_size;

	// ax = absolute x, absolute to the virtual spectrum bitmap
	for (int ax = start; ax < end; ++ax)
	{
		// Derived audio data
		size_t block_index = (size_t)(ax * pixel_ms * provider->GetSampleRate() / 1000) >> derivation_dist;
		float *power = &cache->Get(block_index);

		// Prepare bitmap writing
		unsigned char *px = imgdata + (imgheight-1) * stride + (ax - start) * 3;

		// Scale up or down vertically?
		if (imgheight > 1<<derivation_size)
		{
			// Interpolate
			for (int y = 0; y < imgheight; ++y)
			{
				assert(px >= imgdata);
				assert(px < imgdata + imgheight*stride);
				auto ideal = (double)(y+1.)/imgheight * (maxband-minband) + minband;
				float sample1 = power[(int)floor(ideal)+minband];
				float sample2 = power[(int)ceil(ideal)+minband];
				float frac = ideal - floor(ideal);
				float val = (1-frac)*sample1 + frac*sample2;
				pal->map(val*amplitude_scale, px);
				px -= stride;
			}
		}
		else
		{
			// Pick greatest
			for (int y = 0; y < imgheight; ++y)
			{
				assert(px >= imgdata);
				assert(px < imgdata + imgheight*stride);
				int sample1 = std::max(0, maxband * y/imgheight + minband);
				int sample2 = std::min((1<<derivation_size)-1, maxband * (y+1)/imgheight + minband);
				float maxval = *std::max_element(&power[sample1], &power[sample2 + 1]);
				pal->map(maxval*amplitude_scale, px);
				px -= stride;
			}
		}
	}

	wxBitmap tmpbmp(img);
	wxMemoryDC targetdc(bmp);
	targetdc.DrawBitmap(tmpbmp, 0, 0);
}

void AudioSpectrumRenderer::RenderBlank(wxDC &dc, const wxRect &rect, AudioRenderingStyle style)
{
	// Get the colour of silence
	wxColour col = colors[style].get(0.0f);
	dc.SetBrush(wxBrush(col));
	dc.SetPen(wxPen(col));
	dc.DrawRectangle(rect);
}

void AudioSpectrumRenderer::AgeCache(size_t max_size)
{
	if (cache)
		cache->Age(max_size);
}